Title Taxonomy and ecology of the planktonic diatom family Chaetocerotaceae (Bacillariophyta) from the Adriatic sea Title (croatian) Taksonomija i ekologija planktonskih dijatomeja iz porodice Chaetocerotaceae (Bacillariophyta) u Jadranskom moru Author Sunčica Bosak Mentor Damir Viličić (mentor)Mentor Diana Sarno (komentor) Committee member Nenad Jasprica (predsjednik povjerenstva)Committee member Zrinka Ljubešić (član povjerenstva)Committee member Živana Ninčević Gladan (član povjerenstva)Granter University of Zagreb Defense date and country 2013-11-06, Croatia Scientific / art field, NATURAL SCIENCES Universal decimal classificationUDC ) 55 - Geology. Meteorology. Hydrology 57 - Biological sciences. Physical anthropology. Biodiversity Abstract The cosmopolitan diatom family Chaetocerotaceae abounds in the phytoplankton of coastal regions, comprising ca. 170 species, belonging to two genera, Chaetoceros and Bacteriastrum. In the Adriatic Sea the group is ecologically important represented with ca. 50 species whose identification is often problematic. The species morphology was assessed by analysing the material from cultured strains and the field plankton samples collected at 8 locations along the eastern Adriatic coast from 2006 to 2012. All taxa were studied with light, scanning and transmission electron microscopy. Ecological relationships were investigated: (i) in the coastal area of northern Adriatic (biweekly in 2008 – 2009) (ii) in Krka River estuary (twice a day during six days in July 2010). 49 morphologically distinct taxa were recorded, of which six were affiliated with the genus Bacteriastrum and 43 with genus Chaetoceros with 41 species, two varieties, two tentatively identified and four unknown morphotypes. Five taxa have been reported for the first time for the Adriatic and three emended diagnoses were proposed for Chaetoceros vixvisibilis, Bacteriastrum jadranum and B. mediterraneum. The morphological analysis helped to clear previously common misidentifications of species Bacteriastrum delicatulum/B. furcatum, Chaetoceros contortus/C. compressus, C. decipiens/C. lorenzianus and C. lauderi/C. teres where that in all observed material only first species from the given pair could be identified. The individual morphological characters were classified according to their identification significance with the particular emphasis on comparison and establishing species-specific traits such as resting spore morphology, ultrastructure of the setae and valves. We distinguished 9 different setae structural types in the subgenus Chaetoceros and the same number in the subgenus Hyalochaete. A novel and unique type of colony formation in planktonic marine diatoms was discovered and characterized with the atomic force microscopy (AFM) for Bacteriastrum jadranum which forms colonies by enclosing the cells within the organic network (cell jacket). The phylogenetic analysis of 28S rDNA separated Bacteriastrum furcatum and B. hyalinum in one clade and B. jadranum and B. mediterraneum in the other one. In relation to other Chaetoceros species results imply that that Bacteriastrum species form a lineage within the genus Chaetoceros, but for the drastic changes in the taxonomy there is still a need for a more thorough investigation. The multivariate analysis of seasonal dynamics and ecological relationships showed the permanent presence of chaetocerotacean species in the phytoplankton with with a change in dominance and clear annual succession. The pattern can be partially explained by the environmental parameters, with the temperature, silicate, salinity and phosphate as most important factors driving the community succession.
Abstract (croatian) Kozmopolitska porodica dijatomeja Chaetocerotaceae je brojna u morskom fitoplanktonu obalnih područja te obuhvaća oko 170 vrsta svrstanih u dva roda Chaetoceros i Bacteriastrum. U Jadranu skupina je vrlo raznolika i ekološki značajna te zastupljena s oko 50 vrsta čija je identifikacija često problematična. Morfologija vrsta je određena analizirajući materijal izoliranih kultura stanica i uzoraka planktona prikupljenih na terenu, na 8 lokacija duž istočnojadranske obale u razdoblju 2006 – 2012. Sve svojte su analizirane pomoću svjetlosne, skenirajuće i transmisijske elektronske mikroskopije te vrsta Bacteriastrum jadranum dodatno s mikroskopom atomskih sila (AFM). Ekološki odnosi su istraženi: 1) na jednoj postaji (RV001) u obalnom području sjevernog Jadrana (2008 – 2009, svaka dva tjedna) 2) u području ušća rijeke Krke (dva puta dnevno, tijekom šest dana u srpnju 2010). Određeno je 49 morfološki različitih svojti od kojih 6 pripadaju rodu Bacteriastrum a 43 rodu Chaetoceros, s 41 vrsta, dva varijeteta dvije uvjetno identificirane svojte i četiri nepoznata morfotipa. Tri nadopunjene dijagnoze su predložene za vrste: Chaetoceros vixvisibilis, Bacteriastrum jadranum i B. mediterraneum. Pet vrsta je zabilježeno po prvi put u Jadranu. Razjašnjena je prethodna pogrešna identifikacija kod Bacteriastrum furcatum/B. delicatulum, Chaetoceros contortus/C. compressus, C. decipiens/C. lorenzianus and C. lauderi/C. teres. Analiza je pokazala da je samo prva vrsta iz svakog navedenog para prisutna u analiziranom materijalu. Procijenjena je taksonomska važnost pojedinih morfoloških obilježja s posebnim naglaskom na morfologiju mirujućih spora, ornamentaciju valve i strukturu seta. Razlikuje se 9 različitih tipova struktura seta kod vrsta podroda Chaetoceros i isto toliko kod Hyalochaete. Kod vrste Bacteriastrum jadranum otkriven je i opisan jedinstven i novi način formiranja kolonija kod planktonskih morskih dijatomeja, gdje stanice nisu povezane pomoću fuzije silikatnih struktura nego pomoću optički transparentnog organskog matriksa. Rezultati molekularne filogenetske analize odvojila su Bacteriastrum furcatum i B. hyalinum u jednu grupu te B. jadranum i B. mediterraneum u drugu. U odnosu na ostale vrste Bacteriastrum vrste se grupiraju unutar roda Chaetoceros, ali za drastične taksonomske promjene potrebna su daljnja istraživanja. Multivarijantna analiza sezonske dinamike i ekoloških odnosa pokazala je da su vrste skupine Chaetocerotaceae stalno prisutne u fitoplanktonu a sukcesivno se izmjenjuju tijekom godine. Sukcesijski obrazac se može djelomično objasniti okolišnim parametrima, sa temperaturom, silikatima, salinitetom i fosfatima. Opisi vrsta dijatomeja će olakšati buduću ispravnu identifikaciju u planktonskim uzorcima što će u budućnosti pridonijeti boljoj biogeografskoj rezoluciji i ekološkoj interpretaciji u pelagijalu.
Keywords
marine phytoplankton
diatoms
morphology
taxonomy
succession
Adriatic
Keywords (english)
morski fitoplankton
dijatomeje
morfologija
taksonomija
sukcesija
Jadransko more
Language english URN:NBN urn:nbn:hr:217:859396 Project Number: 119-1191189-1228 Study programme Title: Interdisciplinary doctoral study in Oceanology Type of resource Text Extent 256 str. ; 30 cm File origin Born digital Access conditions Open access Terms of use Public note This doctoral thesis was made in the Division of Biology, Faculty of Science, University of Zagreb under the supervision of Prof. Damir Viličić and in one part in Stazione Zoologica Anton Dohrn in Naples, Italy under the supervision of Diana Sarno. The doctoral thesis was made within the University interdisciplinary doctoral study in Oceanology at the Department of Geology, Faculty of Science, University of Zagreb. The presented research was mainly funded by the Ministry of Science, Education and Sport of the Republic of Croatia Project No. 119-1191189-1228 and partially by the two transnational access projects (BIOMARDI and NOTCH) funded by the European Community – Research Infrastructure Action under the FP7 ‘‘Capacities’’ Specific Programme (Ref. ASSEMBLE grant agreement no. 227799). Created on 2017-11-23 13:48:33
